Effect of free energy on rates of electron transfer between molecules

Miller, John R.; Beitz, James V.; Huddleston, R. Kurt

doi:10.1021/ja00330a004

Cited by 457 publications

(315 citation statements)

References 4 publications

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“…We therefore propose that the major contribution to static quenching derives from photoinduced electron transfer between singlet excited C7o and ground-state donor species separated by much longer distances than involved in an actual ground-state complex. Results of studies on the distance dependence of electron-transfer processes in condensed media have amply revealed the possibility of such long-range electron transfer [23 ]. A useful model for treating such a situation is that provided by a Perrin-type formulation [24], in which all excited species that have a quencher within a distance Ar undergo static quenching, whereas those for which the nearest quencher is beyond that distance do not.…”

Section: Resultsmentioning

confidence: 99%

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Williams

Verhoeven

1992

Chemical Physics Letters

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The fluorescence spectrum and fluorescence quantum yield of C7o were determined in a number of solvents at room temperature. A well resolved fluorescence excitation spectrum, which matches the absorption spectrum, was obtained over a broad wavelength region (250 to 580 nm, in n-hexane). The fluorescence lifetime (627 ps in benzene) was determined, thereby settling the uncertainty about the singlet lifetime of C7o. It is shown that the quenching of the fluorescence by organic electron donors involves both dynamic and static mechanisms. The contribution of the latter is much more pronounced than can be explained from the degree of ground-state charge transfer complexation. Analysis in terms ofa Perrin model indicates that long-range intermolecular electron transfer is important, with a radius of action that increases sharply when the donor oxidation potential is lowered.

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Section: Resultsmentioning

confidence: 99%

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Williams

Verhoeven

1992

Chemical Physics Letters

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“…Both should be exothermic and it is very difficult to predict their relative rates. Cases of slow exothermic electron transfer are now well established (32) and seem to be attributed to the solvent reorganization required according to Marcus theory as the charge moves from one site to the other. Since complete electron transfer is not observed, it is possibly correct to assume that electron transfer does not compete with hydrogen atom transfer.…”

Section: The Mechanism Of Photocleavagementioning

confidence: 98%

“…Many of the usual leaving groups have oxidation potentials higher than that for trimethylamine: bromide (0.7 V vs. SCE in CH3CN) (30), chloride (I. 1 V vs. SCE in CH3CN) (30), dimethylsulfide (1.4 V vs. Ag/AgN03 in CH3CN) (31), and alcohols (no oxidation in CH3CN up to solvent limit) (32). This implies that electron transfer in the pair generated from homolytic cleavage should, in general, be favorable.…”

Section: The Mechanism Of Photocleavagementioning

confidence: 99%

Substituent effects on homolytic versus heterolytic photocleavage of (1-naphthylmethyl)trimethylammonium chlorides

Foster¹,

Gaillard²,

Mathur³

et al. 1987

Can. J. Chem.

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Singlet excited state rate constants have been measured for both the heterolytic and homolytic photocleavage of 3- and 4-methoxy and 3- and 4-cyano (1-naphthylmethyl)trimethylammonium chlorides, 6–10. The results are interpreted in terms of the meta effect or changes in charge distribution upon excitation and the competition between bond cleavage, electron transfer, and hydrogen atom transfer in the contact pairs resulting from the two types of cleavage.

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“…75 To estimate the donor-acceptor (DA) separation for the solvent-separated ion pair, we parametrize this formula with the measured time constant (1/k(r 0 ) ) 0.26 ps) and calculated separation (r 0 ) 0.37 nm, see Figure 4a) of the contact ion pair. Given a typical value of for long-range electron transfer, ) 1.2 Å -1 , 75-78 the DA separation for the solvent-separated ion pair is r ) 4.8 Å.…”

Section: F(t) )mentioning

confidence: 99%

Coherent Electronic and Nuclear Dynamics for Charge Transfer in 1-Ethyl-4-(carbomethoxy)pyridinium Iodide

2006

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Although polaronic interactions and states abound in charge transfer processes and reactions, quantitative and separable determination of electronic and nuclear relaxation is still challenging. The present paper employs the amplitudes, polarizations, and phases of four-wave mixing signals to obtain unique dynamical information on relaxation processes following photoinduced charge transfer between iodide and 1-ethyl-4-(carbomethoxy)-pyridinium ions. Pump-probe signal amplitudes reveal the coherent coupling of an underdamped 115 cm -1 nuclear mode to the charge transfer excitation. Assignments of this recurrence to intramolecular vibrational modes of the acceptor and to modulation of the intermolecular donor-acceptor distance are discussed on the basis of a high-level density functional theory normal-mode analysis and previously observed wave packet dynamics of solvated molecular iodine. Nuclear relaxation of the acceptor induces sub-picosecond decay of the pump-probe polarization anisotropy from an initial value of 0.4 to an asymptotic value of -0.05. Electronic structure calculations suggest that relaxation along the torsional coordinate of the ethyl group is the origin of the anisotropy decay. Electric-field-resolved transient grating (EFR-TG) signal fields are obtained by spectral interferometry with a diffractive optic based interferometer. These measurements show that the signal phase and amplitude possess similar dynamics. Model calculations are used to demonstrate how the EFR-TG signal phase yields unique information on transient material resonances located outside the laser pulse spectrum. This effect can be rationalized in that the real and imaginary parts of the nonlinear polarization are related by the Kramers-Kronig transformation, which allows the dispersive component of the polarization response to exhibit spectral sensitivity over a larger frequency range than that defined by the absorption bandwidth.

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Effect of free energy on rates of electron transfer between molecules

Cited by 457 publications

References 4 publications

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Fluorescence of fullerene-C70 and its quenching by long-range intermolecular electron transfer

Substituent effects on homolytic versus heterolytic photocleavage of (1-naphthylmethyl)trimethylammonium chlorides

Coherent Electronic and Nuclear Dynamics for Charge Transfer in 1-Ethyl-4-(carbomethoxy)pyridinium Iodide

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